The drop locations are not fully understood at this time. The recipes are BOE, which tends to mean "world drop" in TBC, but so far they've only been found off mobs in Blade's Edge Plateau.

Comment by Tenkin

The design for this dropped for me off one of the four 72 elite dragons in Blade's Edge. I farmed those 4 for cloaks and shards for about an hour today. Got one of these and another JC recipe that both wowhead and thottbot listed as not being in the game: Design: Balanced Shadow Draenite: http://www.wowhead.com/?item=31871